#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>

int main()
{
    int a = 0;
    int b = 0;
    int c = 0;
    scanf("%d %d", &a, &b);

    if (a >= b)
    {
        c = a % b;
        if (c == 0)
            printf("%d", b);
        else
            printf("%d", c);
    }
    else
    {
        c = b % a;
        if (c == 0)
            printf("%d", a);
        else
            printf("%d", c);
    }
    return 0;
}